1. Field of the Invention
The present invention relates to a method for fabricating polymer ridged waveguides by using tilted immersion lithography. This fabricating method is simple and stable. It can reduce the fabricating time and cost. In addition, it is suitable for mass production and has wide-ranged applications.
2. Description of the Prior Art
The 45° waveguides structure has been studied for many years. The 45° waveguides can be applied in many fields especially in the fields of photoelectric communication or micro optical system. There are two major fabricating methods for it, namely the diamond blade method, etching method, etc. These methods are described below:
[1] Micro machining. Takashi Satoh et al. utilized the V-shaped diamond blade to fabricate the 45° waveguide by the micro machining. The waveguide structure contains three layers. The top and bottom layers are the epoxy layers. The middle one is the deuterated poly-methylmethacrylate for optical signal transmission.
[2] Reaction ion etching (briefly referred as RIE). Jianhua Gan el al. fabricated the 45° waveguide by the lithographic technology. This kind of 45° waveguide has four layers, namely the oxide layer, epoxy layer, aluminum (Al) layer and photoresist layer. By utilizing the reaction ion etching method, the 45° waveguide can be etched. After removing the aluminum layer, the final structure can be obtained.
[3] Laser etching. Ken-ichiro Tanaka et al. fabricated the 45° waveguide by using the KrF-gas excimer laser. The 45° waveguide contains three layers that are epoxy B, epoxy A and epoxy B. Then, one can use the laser etching technique to remove the unnecessary zone so that the desired 45° waveguide can be made.
[4] Deep lithography with protons (briefly referred as DLP). Jurgen Van Erps et al. utilized the Deep Lithography with Protons (DLP) technology to fabricate the multi-mode polymer waveguide for optical signal transmission. The material used in this waveguide is polymethyl methacrylate (or called PMMA). The light source in manufacturing method is similar to the one used in synchrotron radiation. Then, the exposure for fabrication can be achieved.
However, many disadvantages for the above-mentioned prior arts can be listed below.
[1] This fabricating method is complicated and not stable. The conventional methods require complicated equipment (especially for the deep lithography with protons method requires a huge place). In addition, it fabricating procedures becomes complicated as well. Hence, the size of final product is not stable.
[2] The fabricating time is long and its cost is high. For micro machining, the machining speed is very slow. Once the fabricating time is long, its total cost will be increased. Beside, that the deep lithography with protons method requires a huge place will cause extra cost.
[3] It is not suitable for mass production. It requires lengthy time no matter for the micro machining or for the laser etching. Thus, it is not suitable for mass production.